NEW YORK — Investigators of last weekend’s bombings have released an image of two men who took a suitcase they found on a city street, possibly without realizing a wired pressure cooker they removed from it and left behind could have blown them to bits. Police investigating the bombings in New York and New Jersey have been saying for several days they were looking for the men, who they stressed were being sought as potential witnesses in the case, not as suspects. “They’re not in any jeopardy of being arrested,” Jim Watters, chief of the New York Police Department’s counterterrorism unit, said on Wednesday.